1. Field of the Invention
The present invention relates to a valve, in particular a pressure limiting valve having a spool with spool lands, which form control edges with inflow and outflow grooves in a spool bore/guide.
2. Description of the Related Art
Such valves are known. The valve has, for example, a spool land that is subjected on one side to a pilot pressure and on the other side to a pressure of a main hydraulic system. If the pressure force of the system pressure exceeds the pressure force of the pilot pressure, then the spool begins to move and allows an opening to form at a groove, whereby a flow arises at the control edge which partially reduces the static pressures that previously existed there in the closed state. One also speaks here of the effect of a so-called flow force that results from the now missing pressure force components. With increasing flow at the control edge, additional pressure force components in the opening direction are reduced by the flow, so that the system pressure must rise further in order to open the valve spool further against the constant pilot pressure. In such pressure limiting valves, that results in a rising characteristic curve for the system pressure caused by the increasing volumetric flow. One also speaks here of a rise in the pressure characteristic due to so-called flow forces. The rise of the pressure characteristic thereby results in an increasing pressure rise in the system, which is actually not wanted. Ideally, one would like to achieve constant system pressure across the increase in volumetric flow through the valve.
An object of the present invention is therefore to provide a valve, in particular a pressure limiting valve, with which the pressure rise of the characteristic curve is reduced and the pressure characteristic is thereby improved.